måndag 8 Maj 2006, 19:04

One of the common claims of vegetarians is that eating meat (or specifically red meat) increases the risk of colon cancer. What most of them don't know is that the evidence for this is pretty damn flimsy.

The conclusion is based on a study published in the American Medical associations journal in 2001. That study involved 148,000 adults aged 50-74 who provided information on their meat consumption in 1982 and again in 1992. Of this 148,000, 1667 subjects developed colon cancer.

Taken straight from the study, the result was found as follows “High intake of red meat reported in 1992/1993 was associated with higher risk of colon cancer after adjusting for age and energy intake but not after further adjustment for body mass index, cigarette smoking and other ,”. In plain english, this says that there is no evidence that meat caused any of the cancers. Faced with the prospect of getting a no result (a big no no if you want to keep on getting funding) the researchers took a razor to their data and cut vast sections out until they could find a result.

What they did was pick on three specific types of colon cancer where there was something resembling a result. Meat was supposedly found to increase the cancer risk in the three types by 50%,53% and 71% respectively. Sounds impressive, not really, in statistics increases of less than 100% are of borderline significance and highly likely to be the result of chance. They had after all sliced their data so much that with the specific types of cancer they were now talking about 79 cases out of 148,000 people.

The weak statistics are made even worse by unreliable data collection. No data was collected on how much the subjects smoked, drank and exercised (smoking, drinking alcohol and lack of exercise are all proven to cause colon cancer, without amounts there is no way to determine if any of these factors caused the colon cancer). Also family history of colon cancer was not even considered, even though this is believed to be a major risk factor.

So to conclude, all we really can tell from this study is that the researchers were too busy looking for media attention and their next grant to present honest facts in the study. Of course the media picks up on it because it gives them a sensational headline. But the stats are weak and inconsistent and essentially prove no link, you can grill up your steak safe in the knowledge that there is no increased cancer risk.